﻿using System;

/* Copyright (c) 2010 CBaxter
 * 
 * Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), 
 * to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, 
 * and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:
 * 
 * The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.
 * 
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, 
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER 
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS 
 * IN THE SOFTWARE. 
 */

namespace Xpedite
{
  internal class AsynchronousCallWrapper<TResult>
  {
    private Func<TResult> _valueRetriever;
    private readonly Object _syncObject = new Object();

    public AsynchronousCallWrapper(Func<TResult> retriever)
    {
      Verify.NotNull(retriever, "retriever");

      IAsyncResult asyncResult = retriever.BeginInvoke(null, null);

      _valueRetriever = () =>
      {
        try
        {
          TResult result = retriever.EndInvoke(asyncResult);

          _valueRetriever = () => result;

          return result;
        }
        catch (Exception ex)
        {
          _valueRetriever = () => { throw new XpediteException(ex.Message, ex); };

          throw new XpediteException(ex.Message, ex);
        }
      };
    }

    public TResult Result
    {
      get
      {
        lock (_syncObject)
          return _valueRetriever.Invoke();
      }
    }
  }
}
